Method and means for finishing timepiece balance wheels



Oct. 18,1932. GGALLAY 1,883,779

METHOD AND MEANS FOR FINISHING TIMEPIECE BALANCE WHEELS Filed May 25, 1931 P:.:.:1:::Wi 1? pvverv 10K ed. WW Q Patented Get. 18, 1932 UNITED STATES GEORGES GALLAY, or LE sEN rIER, WITZERLAND I METHOD AND MEANS FOR ErmsnmGf'rIMErIEcE BALANCE wEEELs. I

Application filed May 25, 1931, Serial No. 539,890, and in Switzerland August 12, 1930.

This invention relates to a method and means for finishing timepiece balance wheels and has as its primary object to'provide balance wheels having rigorously circular rims which are strictly concentric to the axis of the wheel.

It is also an object of the invention to, provide means for'accurately finishing the inner surface of the rim of the balance wheel.

In the drawing, which represents a suitable embodiment of an apparatus for carrying the invention into efiect,

Figure 1 is a plan view of the apparatus;

Figure 2 is an elevation; I

Figure 3 is an end View of a part of the apparatus with the balance wheel to be fin. ished secured thereto.

The shaft 1 can be rotated by any appropriate means about its longitudinal axis and carries at its end and centered relative to its axis, a balance wheel A which is to be finished. A tool carrier 2 is disposed opposite the shaft 1 and can slide in a longitudinal guide 3 provided on the frame 11 of the 2 machine. This tool carrier is adapted to receive a cutter l and also supports a transverse arm 5 provided with-a cam 6. The opposite end of the tool carrier supports a transverse arm 7 to each end of which there is fixed a pin 12. Similar pins 9 are fixed to'the guide 3 and springs 8 connecting'each pair of pins 8 and 12 constantly urge the arm 7 and the tool carrier 2 towards the shaft 1. l l

The end face of the shaft 1 carries diametrically opposite each other two fingers 10. The balance wheel A is disposed in such a way on the end face of the shaft 1 that the longitudinal axis of its arm B coincides with the connecting line of the centers of the two fingers 10.

The balance wheel which is already cut out, is attached to the shaft 1 and the cutter 4 is disposed so that its cutting edge engages the inner surface E of the balance wheel rim. The cutting movement is then produced by rotation of the shaft 1, while the feed motion may be given the tool carrier 2 by any known means. At each half turn of the shaft 1 one of the fingers 10 acts on the cam 6 and pushes the tool carrier backwards againstv the action of the springs 8 for an amount which is equal to the thickness-of the arm B of-the balance wheel; this arm vdoes therefore not prevent the movement of rotation of the shaft 1, the cutterbeing pushed back while the arm passes infrontofit. f I

By means of-the described apparatus one obtains balance wheels which are finishedon the inner surface of their rim, this latter being 0 face of the rims of wheels having arms or spokes, which consists in centering the wheel on a rotatable work carrier, rotating the work carrier with the wheel thereon, feeding a tool radially against the inner surface of the rim of the wheel, and axially shifting the tool away from and towards the work carrier in timed relation to the rotation thereof to pro-. vide for the passage of the spokes of the wheel in front of the tool.

2. The method of finishing the inner surface of rims of wheels having arms or spokes, which consists in centering the wheel on a- 35 rotatable work carrier, rotating the work car- I ri er with the wheel thereon, feeding a cutting tool radially against the inner surface ofthe rim of the wheel, and effecting relative axial movement between thework carrier and the1 between the tool and the work carrier, and

efi'ecting relative axial movement between the tool and the work carrier in timed relation to the movement of rotation to provide for the passage of the balance wheel arms in front of the tool.

4. A lathe for finishing the inner surface of the rim of Wheels having arms or spokes, comprising a rotatable work carrier adapted to have the wheel centered on a face thereof, fingers projecting from said face and corresponding in number to the number of spokes of the wheel to be finished, said fingers being situated exteriorly of the wheel rim when centered on this face and on the longitudinal axis of each spoke thereof, a tool disposed to 7 work on the inner face of the wheel rim, a

tool carrier, spring means acting to approach the tool carrier to the work carrier, and abutting means on the tool carrier situated in a predetermined position relative to the tool and coacting with said fingers on the work carrier for effecting relative axial movement between the tool carrier each time a spoke of the wheel approaches the tool.

, In testimony whereof I aflix my signature.

GEORGES GALLAY. 

